A "Check Third Brake Light" message appeared recently on my 2012.5 C2S whenever the spoiler retracted. I found a couple of forum postings here about DYI repair to frayed wires, involving removal of the spoiler, taping wires and replacing interfering plastic parts.

One nearby dealer didn't inspect but advised a new wiring harness would be needed for ~ $650.

The dealer where I bought the car advised they had fixed a couple of these. They charged for labor to R&R the spoiler, repair the frayed wire and attach it at the frayed end with new connectors.

 

It is really disgusting how stealership service really tries to rip you off. Told new harness without inspecting when it turns out to be no more than a reconnection of a few wires. Geeze, I mean really.

Been taking my Mercedes for inspection at the local dealership for years. While under warranty, got inspections with no issues whatsoever. Continued to get my car inspected there after the warranty ended - all of a sudden there was a problem during every inspection. One year it was a loose belt ($550), another year leaking differential fluid ($1700), another year faulty controller (another $500 or so). I never authorized them to fix any of the "supposed" issues and the car runs fine. Funny how these problems happen all of a sudden after warranty ends, eh? And you wonder why they have a bad reputation. It is really disgusting.

 

Same issue happened to me. I had to bring in my car 3 times, supposedly the first two times they replaced the harness, I still had issues. The third time they replaced the light itself, it was finally resolved, thankfully I was under warranty or else it would have been a $2,000 + down the drain.

 

Just got a quote to change out the rear pads and rotors on a Fiat 500 Abarth - best part of $500 at a local indie. Bought the parts for $100 and did it myself while my son helped.

They are all at it. The reputation is sadly deserved across the industry.

 

 

Pretty easy DIY. About an hour to do (spoiler setting on the bench) and the cost of the spoiler harness, as patching will only last a few months (no special tools needed, other than torx). And while you're at it you'll likely notice a broken assist spring stay in your spoiler mechanism

 

Zoomie-

I can' find the DYI description post I once saw, but it sounded like your description of the fix. If that was you could you post the link for Jabs1542?

 

My apologies, it wasn't mine.

 

Did it ever occur to you that some of those items came up as your car aged and accumulated more miles? Not to mention the fact they're warranty items and the dealership would have been paid by Mercedes for doing the warranty work if they did occur while you were in the warranty period.

 

95% of people are either incapable or unwilling to do the work themselves. I can't blame the indie for pricing at what the market will allow. Either pay it or do what you and I would do and fix it yourself.